I would encourage all of you to read Fred Moseley’s case for the labor theory of value and the problems he has with Branko Milanovic’s interpretation of it. This may seem like an exercise in Marxist antiquarianism, but the underlying questions are important.
For what it’s worth, my own view is that Fred is absolutely correct in arguing for the centrality of a theory of profit in any analysis of capitalist economies. I’m less sure the LTV does this, however, since at best it’s simply an accounting relationship. By contrast, Marx’s bargaining hypothesis, based on the reserve army of labor, has stood the test of time rather well, even if it now goes under the heading of the wage curve.
I think the time may also be coming to revisit the debate between Marx and Proudhon over the issue of profit and exploitation. Proudhon argued for economies of scale, according to which workers would receive their marginal products, but the sum did not exhaust the value of production. This was the basis for his advocacy of coops. Of course, Proudhon did not have the math to express this with precision, leaving Marx with the impression that it was all a big muddle.
Most economists would now be inclined to side with Pierre-Joseph, and I would go along too, at least partly. But the economy of scale argument also depends on the assumption there is normally a single efficiency optimum for the enterprise, which I would dispute strongly. Reformulating Proudhon for a more complex vision of the economy, one that is multi-peaked and requires discovery and planning as well as scale, is an important task. As both Marx and Proudhon would have understood, the theory of profit-making is at the core of figuring out how capitalism works and envisioning pathways beyond it.